T.pick

A structure: a copy of an object schema with only the fields you name.

const UserSchema = T.object({
  id: T.number.integer.sequence,
  first: T.string.whereby({ length: { min: 1, max: 12 } }),
  last: T.string.whereby({ length: { min: 1, max: 12 } }),
  email: T.string.whereby({ length: { min: 5, max: 30 } }),
});
 
const ContactSchema = T.pick(UserSchema, ["id", "email"]);
// { id: number; email: string }

The source can be an object schema or a built object Fabricator. Naming a field the source doesn't have is a type error, and it throws at runtime too.

Fields keep their order from the source.

Computed fields

A kept computed field still needs the fields it reads. If you didn't keep them, they are fabricated anyway and left out of the result:

const NamedUserSchema = UserSchema.refine(({ compute }) => ({
  name: compute(T.string)
    .from(["first", "last"])
    .as(({ fabricated }) => `${fabricated.first} ${fabricated.last}`),
}));
 
T.pick(NamedUserSchema, ["id", "name"]);
// { id: number; name: string }, with first and last fabricated for `name`

Declare dependencies with .from so only those fields are kept. A computed field without .from can read the whole object, so every field it could read is kept.

What doesn't carry over

The result is a new object schema. The source's own .as(produce) and any .adapt(...) on the whole object are dropped, because both describe the source's full shape. Each kept field keeps its own .adapt(...) and .override(...) values.

For the inverse, see T.omit.